Resurrecting a Roketa MC54-250B

[bull]

Thought you might find it interesting to follow along as I resurrect a customers' Rokets MC54- 250B aka a Jonway YY250T.

He is a new owner of this scooter from a barter transaction with someone. He does not have any keys and it has sat for many months not running.

A visual exam of the scooter revealed many broken body panels, screws missing, wrong bolts in certain places, battery dead, flat tires and missing windscreen. Plus the typical body scratches from being dropped.

After removing the lower dash panel, and side body panels the following was noted:

fuse link @ battery destroyed and connected direct to Batt +, battery feed wire into ignition switch melted, switched battery power wire melted, igntion switch connector melted, and body harness half missing (removed), and a few other lower gauge wires literally melted in half.

Has a new regulator, starter solenoid, and damaged wiring connecter to regulator.

This particular scooter has the same CF250 engine as used in the Honda Helix and the Diamo Velux. The Diamo Velux of which I am resurrecting one of those for someone else.

First order of business, air up the tires, disconnect the battery and trickle charge for about 16 hours @ 1/2 amp.

While the battery is charging, remove the ignition switch, disassemble and check for damage.

If you have any questions or thoughts, feel free to express them.

[bull]

The battery appears to be weak but ok for testing purposes only.

The ignition switch had no electrical damage but did have some corrosion on the contacts from water, which was easily cleaned with sanding, then re coating with dielectric silicone grease.

I inserted a 2Amp short circuit finder into the ignition battery feed circuit to test some components before replacing the burned wires. The two amp is low enough enough power to not harm anything, but high enough for dynamic circuit testing.

A note about ground wire circuit color; black is used in the USA, brown in Europe, green in China-- these are sold colors w/o tracers.

Checking the chassis wiring diagram shows that the main power circuit is 20amps (D 5.5 in diagram) and the switched is 15 amps. The location of the main power fuse is drawn to be in the starter solenoid (relay), but this is false.

Jumpered the feed and switch power circuits. Depressed brake lever & checked power to starter solenoid using a circuit probe- No Power. Depressed other brake, - no power. Checked power @ dash wiring connector, both circuits - ok. Checked power into micro switches - ok. Power out - none, switches bad.

Checking starter solenoid, but first remove the plug and add a little oil to cylinder to lube rings, it has been sitting too long. Just good precaution.

Disconnected one brake micro switch, jumpered, checked power at starter solenoid - ok. Momentarily depress start button, starter engaged.

Checked fuse block (4 fuses) 3 ok. 4th is AC powered for lights from ac generator (stator). circuit ok. Ac generator - unknown.

Testing for ignition primary: tested power and grounds to CDI and ignition coil. All ok.

Here is a little tip when checking power and grounds with a circuit probe. Normally you would check power by grounding the circuit probe and probing a power wire. But to dynamically test ground circuits, connect the probe to a power feed (battery +) and then probe the grounds.

Bypassed solenoid circuit to crank engine testing spark. No spark. Tested AC power from crank sensor with DMM- weak output. Tested coil primary & secondary windings- no shorts-ok.

Cranking speed is very slow, even with the plug out and this could influence the crank sensor output.

Next on the agenda, get approval for replacing the burned wires, adding an ATC 20 amp inline fuse into power circuit, and a replacement battery.

Here are some things to help others on the forum:

Wiring diagram- this is one of the best I have seen and it is extremely close to all GY6 scooters (50cc & 150cc) as well.





Photo above of an acceptable DMM & circuit probe for the casual user.

[bull]

Replaced the two power feeds, and installed a mini ato smart fuse holder and 20amp fuse. All splice joints and terminals were silver soldered and double shrink wrapped.

Installed a new ign switch wiring connector on the chassis side. after the customer returns with the rekeyed ign lock, I'll install a new connector onto the elec half of the switch,

the connector I chose is a 6 way by Hoppy # 47995.

Then connected up a 10amp Napa boost charger, spun the engine over and it fired right up. Let it run for about 30 or 40 minutes-- seems very strong, but a little noisy. Might be ok, after it has a few hours run time and a first maintenance service.

Checked the ac generator output and so far it looks weak, shows max charge of 13.4Vdc @ 4k rpm. Still waiting on a new battery supplied by customer, perhaps that will help the charge voltage climb to nominal levels.

Starter even with boost seemed to be laboring, most likely damaged by previous repairer using something w/ too much power to boost.

Went to PS distro center, picked up a bolt kit so that I can replace the missing, and damaged bolts. While there I learned they discontinued the TPGS 803 (classic model) and they are discontinuing the large pan headed 6mm Phillips screws.

Returned and started reassembling the body panels and repairing & aligning as I install.

Customer wants to know about replacement windscreen, suppose a search might yield an oem unit.

[bull]

Here are some photos of the burned circuits. The links provided will access full resolution photos for easy viewing that can be downloaded if you want.
I did not attach the photos in the post as they might cause forum posting problems.

The wire @ the bottom (red on each end through a black tube) is the fuse link wire @ the battery. The upper red wire is the main power continuation to the switch.

The black wire with a ring terminal was the alarm system ground melted in half.

The other black wire is the switched power feed.

On a cautionary note to those that have never dealt with this, the best repair is separating the harness, removing one wire @ a time and checking all the other wires in the harness for damage. If I had not followed this practice I would have missed where the CDI shut down signal wire (blk w/ white tracer) had a bare area, that could have caused a problem later on.

Full size photo links:

http://aerox.us/roketa/roketa-burned-wiring.jpg

http://aerox.us/roketa/roketa-burned-wiring2.jpg

[Shadowfire]

It does look like the wires were not properly protected, then damaged and shorted to each other.

I'd like to say that someone else before you messed with the bike, but after seeing the condition mine was in, that someone else was probably someone at the factory.

[bull]

The insulation was good @ the factory, they pulled each individual 16 awg wire through a loom. Even the splice joints were done well. The wire insulation melted because the wires overheated. This was simply a case of too much power flowing through them or someone cross connected when jumping it. The later is what I suspect most, since the ground wire for the alarm was literally melted in half. It was 22 awg wire.

Got the ignition switch back from the customer, checked my cleaning of the switch and it was good. The switch wire colors was a little surprising though.

These switches like most others only have two circuits in them: one for run and another for shut down. The run circuit was red input and red w/ white tracer for switched power (the scooter chassis switched power is black). The shut down (CDI circuit) was black w/ white tracer and black (scooter chassis ground is green).

[bull]

Here are some photos of the scooter. which will be picked up shortly by the owner. He will be riding it home!

[novaraptor]

always a pleasure seeing one kept or put back on the road.. Thanks for the share..

[bull]

Thank you for the comment.

I just acquired two Diamo Velux scooters that I intend to fully restore to their former glory and make some improvements along the way to make them faster, more reliable and protect the body panels.

Was not sure if this kind of thing would interest anyone. Just restoring the scooters and upgrading them takes a lot of time, but IF I were to post almost a journal others might find it helpful. Before I do something like that I would want to know there is enough interest from forum members to justify the extra work.

[kz1000st]

I'm always interested to see a story that puts scooters, especially Chinese, back on the road. Too many two wheeled devices just end up in corners in a junkyard. Most 70s Japanese bikes ended that way.

[bull]

After a lot of thought, I have decided to post a journal of the restoration of one of the Diamo Velux 150cc scooters.

Was thinking of where on the forum to place the info, and since there is not a section titled "Restoration", the next best choice would be "Custom Builds or under the 150" channel. But both imply the wrong thing in this case IMO.

Where do you think would be best?

[Neltech]

Hi guys just picked up this roketa mc54 ....after checking over my new purchase found out the bike was not charging after finding the stator shorted out ,. I replaced with a new unit after removing right side engine cover and reassembled everything now bike with not accelerate , but will start and idle .....very weird was idling good and acceleration was fine before the repair.

[bull]

Originally Posted by Neltech

Hi guys just picked up this roketa mc54 ....after checking over my new purchase found out the bike was not charging after finding the stator shorted out ,. I replaced with a new unit after removing right side engine cover and reassembled everything now bike with not accelerate , but will start and idle .....very weird was idling good and acceleration was fine before the repair.

Will need to know more. Is your a 250 or a 250b?

IOW.. is it a Honda or Yamaha clone engine?

[jfmjr442]

2006 Roketa 250cc linhai engine resurrected after 3 years. For sale in Rockville MD. Runs great and very fast

John

[Shadowfire]

I'm kinda stumped on this. If you put everything back together correctly, and didn't mess with the carburetor screws, then the only thing I can think of is maybe you didn't install the stator in the exact same position? If the stator can be adjusted/rotated, this will affect the spark plug timing. (Disclaimer: I am not familiar with your engine.)